This is a library of perfboard and single-sided PCB effect layouts for guitar and bass. I'm not an electrical engineer by any stretch of the imagination, just a DIY'er who likes drawing layouts. It is meant for the hobbyist (so commercial use of any of these layout is not allowed without permission) and as a way to give back to the online DIY community.

Wednesday, March 25, 2015

MicTester Buzz-Alike

Like many of the old germanium fuzzes, the Burns Buzzaround can be difficult to get right. It also uses 3 sometimes costly germanium transistors, and unless you also build a power inverter or use NPN transistors, you can't daisy chain it with other negative ground effects. To get around these hurtles, Mictester designed a work-a-like of the Buzzaround using only one (NPN) germanium transistor and germanium diode alongside a dual op-amp. Here's mictester's description of this circuit:

"The original consisted of two stages - a two-transistor amplifier and a distortion stage that could have both the amount of signal sent to it and the bias point adjusted by external controls. The third control was a crude tone control which fed the output. Originally, the output was unbuffered, and the leads and amplifier following would load the unit, and the top end would be rolled off, and often the tone control would have little effect. 

The first stage in the sound-alike is just a high input impedance op-amp gain stage. You may wish to increase the gain by increasing the value of the feedback resistor, but it sounds pretty good as shown. In the original, the first stage didn't really have much effect on the sound - it just amplified it enough to drive the following stage into conduction.

The heart of the beast is the germanium transistor stage. Apart from using an NPN transistor, this remains true to the original (why screw up a classic?), and still gives a wide range of sounds from the thin toppy fuzz beloved of sixties bands through to gated spluttery farts, with smooth warm distortion sounds in between!

The final stage is just a buffer - it isolates the tone circuit from the outside world, and allows a full range of control from muffled to glass-shattering!"

1 comment:

  1. Thanks for the neat layout. It went together quickly and easily, and gives the range of sounds that Mictester originally described. I had a chance to try my modernised one against an original: He got it right! The modern take on the circuit sounds pretty much exactly like the original, except that it hisses less! It also drives long leads better and plays nicely with a wah pedal. It's a very 60s sound, but none the worse for that!
    A highly recommended build if you can find a nice germanium NPN transistors for it.